Iron-Based Binary Catalytic System for the Valorization of CO2 into Biobased Cyclic Carbonates

The atom economic conversion of epoxidized vegetable oils and fatty acid derivatives with CO2, into cyclic carbonates permits the synthesis of novel oleo compounds from renewable resources as well as the valorization of CO2, as a Cl-building block. Organic phosphorus salts proved to be selective catalysts for this reaction. In a widespread screening 11 inexpensive and nontoxic iron salts were evaluated as cocatalysts to enhance the reaction rate. In the presence of 0.25 mol % iron chloride the selectivity and conversion were significantly improved. The reaction parameters were optimized under solvent-free conditions, and the scope and limitation were evaluated for 9 epoxidized fatty acid esters and 4 epoxidized vegetable oils. The biobased carbonates were isolated in excellent yields up to 95% and can be considered to be based on 100% CO2, in respect to carbon. This binary catalyst system features high efficiency and plain simplicity while valorizing CO2, into cyclic carbonates based on renewable feedstocks.